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History of chemistry
The history of chemistry encompasses a span of time reaching from ancient history to the present. By 1000 BC, the ancient civilizations were using technologies that would form the basis of the various branches of chemistry. Extracting metal from their ores, making pottery and glazes, fermenting beer and wine, making pigments for cosmetics and painting, extracting chemicals from plants for medicine and perfume, making cheese, dying cloth, tanning leather, rendering fat into soap, making glass, and making alloys like bronze. Philosophical attempts to explain the nature of matter and its transformations failed. Alchemy, the predecessor of modern chemistry, was also unsuccessful in explaining the true nature of matter. However, the work of Jabir ibn Hayyan gave alchemy a more scientific approach with a strong emphasis on laboratory experimentation and recording results, thus setting the stage for modern chemistry, which begins to emerge when a clear distinction is made between chemistry and alchemy by Robert Boyle in his work The Sceptical Chymist (1661). Chemistry then becomes a full-fledged science when Antoine Lavoisier develops his law of conservation of mass, which demands careful measurements and quantitative observations of chemical phenomena. So, while both alchemy and chemistry are concerned with the nature of matter and its transformations, it is only the chemists who apply the scientific method. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs.Selected Classic Papers from the History of Chemistry From fire to atomism Arguably the first chemical reaction that was used in a controlled manner by mankind was fire. However, for millennia, in absence of a scientific understanding, fire was simply a mystical force that could transform one substance into another (burn the wood, or boil the water) while producing heat and light. Fire affected many aspects of early societies, ranging from the most simple facets of everyday life, such as cooking and habitat lighting, to more advanced technologies, such as pottery, bricks, and melting of metals to make tools. Philosophical attempts to rationalize why different substances have different properties (color, density, smell), exist in different states (gaseous, liquid, and solid), and react in a different manner when exposed to environments, for example to water or fire or temperature changes, led ancient philosophers to postulate the first theories on nature and chemistry. The history of such philosophical theories that relate to chemistry, can probably be traced back to every single ancient civilization. The common aspect in all these theories was the attempt to identify a small number of primary elements that make up all the various substances in nature. Substances like air, water, and soil/earth, energy forms, such as fire and light, and more abstract concepts such as ideas, aether, and heaven, were common in ancient civilizations even in absence of any cross-fertilization; for example in Greek, Indian, Mayan, and ancient Chinese philosophies all considered air, water, earth and fire as primary elements. The rise of metallurgy The earliest recorded metal employed by humans seems to be gold which can be found free or "native". Small amounts of natural gold have been found in Spanish caves used during the late Paleolithic period, c. 40,000 BC. Silver, copper, tin and meteoric iron can also be found native, allowing a limited amount of metalworking in ancient cultures.Photos, E., 'The Question of Meteorictic versus Smelted Nickel-Rich Iron: Archaeological Evidence and Experimental Results' World Archaeology Vol. 20, No. 3, Archaeometallurgy (February 1989), pp. 403–421. Online version accessed on 2010-02-08. Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as "Daggers from Heaven".W. Keller (1963) The Bible as History, p. 156 ISBN 0-340-00312-X During the early stages of metallurgy, methods of purification of metals were sought, and gold, known in ancient Egypt as early as 2600 BC, became a precious metal. The discovery of alloys heralded the Bronze Age. After the Bronze Age, the history of metallurgy was marked by which army had better weaponry. Countries in Eurasia had their heyday when they made the superior alloys, which, in turn, made better armour and better weapons. This often determined the outcomes of battles. Arguably the first chemical reaction used in a controlled manner was fire. However, for millennia fire was seen simply as a mystical force that could transform one substance into another (burning wood, or boiling water) while producing heat and light. Fire affected many aspects of early societies. These ranged from the simplest facets of everyday life, such as cooking and habitat lighting, to more advanced technologies, such as pottery, bricks, and melting of metals to make tools. It was fire that led to the discovery of glass and the purification of metals which in turn gave way to the rise of metallurgy. During the early stages of metallurgy, methods of purification of metals were sought, and gold, known in ancient Egypt as early as 2900 BC, became a precious metal. Bronze Age Certain metals can be recovered from their ores by simply heating the rocks in a fire: notably tin, lead and (and at a higher temperature) copper, a process known as smelting. As often happens with the study of prehistoric times, the ultimate beginnings cannot be clearly defined and new discoveries are continuous and ongoing. . Boxes colors: arsenic is in brown, copper in red, tin in grey, iron in reddish brown, gold in yellow, silver in white and lead in black. Yellow area stands for arsenic bronze, while grey area stands for tin bronze.]] These first metals were single ones or as found. By combining copper and tin, a superior metal could be made, an alloy called bronze, a major technological shift which began the Bronze Age about 3500 BC. The Bronze Age was period in human cultural development when the most advanced metalworking (at least in systematic and widespread use) included techniques for smelting copper and tin from naturally-occurring outcroppings of copper ores, and then smelting those ores to cast bronze. These naturally-occurring ores typically included arsenic as a common impurity. Copper/tin ores are rare, as reflected in the fact that tin bronzes were rare in Western Asia before 3000 BC. After the Bronze Age, the history of metallurgy was marked by armies seeking better weaponry. Countries in Asia prospered when they made the superior alloys, which, in turn, made better armor and better weapons. This often determined the outcomes of battles. Iron Age The extraction of iron from its ore into a workable metal is much more difficult than copper or tin. It appears to have been invented by the Hittites in about 1200 BC, beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines.B. W. Anderson (1975) The Living World of the Old Testament, p. 154, ISBN 0-582-48598-3 In other words, the Iron Age refers to the advent of ferrous metallurgy. Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, and Anatolia (Turkey), Ancient Nok, Carthage, the Greeks and Romans of ancient Europe, medieval Europe, ancient and medieval China, ancient and medieval India, ancient and medieval Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the blast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows.R. F. Tylecote (1992) A History of Metallurgy ISBN 0-901462-88-8Temple, Robert K.G. (2007). The Genius of China: 3,000 Years of Science, Discovery, and Invention (3rd edition). London: André Deutsch. pp. 44–56. ISBN 978-0-233-00202-6. Much of the early development of purification methods is described by Pliny the Elder in his Naturalis Historia. He made attempts to explain those methods, as well as making acute observations of the state of many minerals. Significant progress in metallurgy and alchemy was made in ancient India. Will Durant wrote in The Story of Civilization I: Our Oriental Heritage: Atomism Atomism can be traced back to ancient Greece and ancient India. Will Durant (1935), Our Oriental Heritage: Greek atomism dates back to 440 BC, as what might be indicated by the book De Rerum Natura (The Nature of Things) written by the Roman Lucretius in 50 BC. In the book was found ideas traced back to Democritus and Leucippus, who declared that atoms were the most indivisible part of matter. This coincided with a similar declaration by Indian philosopher Kanada in his Vaisheshika sutras around the same time period. In much the same fashion he discussed the existence of gases. What Kanada declared by sutra, Democritus declared by philosophical musing. Both suffered from a lack of empirical data. Without scientific proof, the existence of atoms was easy to deny. Aristotle opposed the existence of atoms in 330 BC. Distillation Early types of distillation were known to the Babylonians in Mesopotamia (in what is now Iraq) from at least the 2nd millennium BC.Martin Levey (1956). "Babylonian Chemistry: A Study of Arabic and Second Millennium B.C. Perfumery", Osiris 12, p. 376-389. Archaeological excavations in northwest Pakistan have yielded evidence that the distillation of alcohol was known in the Indian subcontinent since 500 BC, but only became common between 150 BC - 350 AD.Allchin 1979 Primitive tribes of India used a method of distillation for producing Mahuda liquor. This crude and ancient method is not very effective.Forbes 1970: 53-54 Distillation was later known to Hellenistic Egyptian alchemists of Alexandria by the 1st century AD, and the later development of large-scale distillation apparatus occurred in response to demands for spirits. According to K. B. Hoffmann the earliest mention of "destillatio per descensum" occurs in the writings of Aetius, a Greek physician from the 5th century.Distillation - LoveToKnow 1911 Hypatia of Alexandria is credited with having invented an early distillation apparatus,Biology, Joan Solomon, Pat O'Brien, Peter Horsfall, Nelson Thornes, p.41 and the first clear description of early apparatus for distillation is given by Zosimos of Panopolis in the fourth century. The invention of highly effective "pure distillation" is credited to Arabic and Persian chemists in the Middle East from the 8th century. They produced distillation processes to isolate and purify chemical substances for industrial purposes such as isolating natural esters (perfumes) and producing pure alcohol.Robert Briffault (1938), The Making of Humanity, p. 195: The first among them was Jābir ibn Hayyān (Geber), in the 8th century, who is credited with the invention of numerous chemical apparatus and processes that are still in use today. In particular, his alembic was the first still with retorts which could fully purify chemicals, a precursor to the pot still, and its design has served as inspiration for modern micro-scale distillation apparatus such as the Hickman stillhead.Microscale Laboratory Techniques - Distillation from McMaster University The isolation of ethanol (alcohol) as a pure compound through distillation was first achieved by the Arab chemist Al-Kindi (Alkindus). Petroleum was first distilled by the Persian alchemist Muhammad ibn Zakarīya Rāzi (Rhazes) in the 9th century, for producing kerosene, while steam distillation was invented by Avicenna in the early 11th century, for producing essential oils. As the works of Middle Eastern scribes made their way to India and became a part of Indian alchemy, several texts dedicated to distillation made their way to Indian libraries. Among these was a treatise written by a scholar from Baghdad, al-Khwarizmi al-Khati, in 1034 titled Ainu-s-Sana'ah wa' Auna-s-Sana'ah.Forbes 1970: 42 Scholar Al-Jawbari travelled to India.Forbes 1970: 45 By the time of the writing of the Ain-e-Akbari, the process of distillation was well known in India.Forbes 1970: 54 Distillation was introduced to medieval Europe through Latin translations of Arabic chemical treatises in the 12th century. In 1500, German alchemist Hieronymus Braunschweig published Liber de arte destillandi (The Book of the Art of Distillation)Magnum Opus Hermetic Sourceworks Series the first book solely dedicated to the subject of distillation, followed in 1512 by a much expanded version. In 1651, John French published The Art of Distillation the first major English compendium of practice, though it has been claimed''Industrial Engineering Chemistry'' (1936) page 677 that much of it derives from Braunschweig's work. This includes diagrams with people in them showing the industrial rather than bench scale of the operation. Early alchemy The philosopher's stone and the rise of alchemy Many people were interested in finding a method that could convert cheaper metals into gold. The material that would help them do this was rumored to exist in what was called the philosopher's stone. This led to the protoscience called alchemy. Alchemy was practiced by many cultures throughout history and often contained a mixture of philosophy, mysticism, and protoscience. The practice of alchemy arose independently in several civilizations: Egypt, India, and China. Egyptian alchemy in particular gave rise to Islamic alchemy, which in turn gave rise to European alchemy. Alchemy not only sought to turn base metals into gold, but especially in a Europe rocked by bubonic plague, there was hope that alchemy would lead to the development of medicines to improve people's health. The holy grail of this strain of alchemy was in the attempts made at finding the elixir of life, which promised eternal youth. Neither the elixir nor the philosopher's stone were ever found. Also, characteristic of alchemists was the belief that there was in the air an "ether" which breathed life into living things. Practitioners of alchemy included Isaac Newton, who remained one throughout his life. Problems encountered with alchemy There were several problems with alchemy, as seen from today's standpoint. There was no systematic naming system for new compounds, and the language was esoteric and vague to the point that the terminologies meant different things to different people. In fact, according to The Fontana History of Chemistry (Brock, 1992): The language of alchemy soon developed an arcane and secretive technical vocabulary designed to conceal information from the uninitiated. To a large degree, this language is incomprehensible to us today, though it is apparent that readers of Geoffery Chaucer's Canon's Yeoman's Tale or audiences of Ben Jonson's The Alchemist were able to construe it sufficiently to laugh at it. Chaucer's tale exposed the more fraudulent side of alchemy, especially the manufacture of counterfeit gold from cheap substances. Less than a century earlier, Dante Alighieri also demonstrated an awareness of this fraudulence, causing him to consign all alchemists to the Inferno in his writings. Soon after, in 1317, the Avignon Pope John XXII ordered all alchemists to leave France for making counterfeit money. A law was passed in England in 1403 which made the "multiplication of metals" punishable by death. Despite these and other apparently extreme measures, alchemy did not die. Royalty and privileged classes still sought to discover the philosopher's stone and the elixir of life for themselves. There was also no agreed-upon scientific method for making experiments reproducible. Indeed many alchemists included in their methods irrelevant information such as the timing of the tides or the phases of the moon. The esoteric nature and codified vocabulary of alchemy appeared to be more useful in concealing the fact that they could not be sure of very much at all. As early as the 14th century, cracks seemed to grow in the facade of alchemy; and people became sceptical. Clearly, there needed to be a scientific method where experiments can be repeated by other people, and results needed to be reported in a clear language that laid out both what is known and unknown. From alchemy to chemistry , from Marcelin Berthelot, Collection des anciens alchimistes grecs (3 vol., Paris, 1887-1888).]] Islamic alchemy and emergence of experimental chemistry (Geber), an Arabic alchemist whose experimental research laid the foundations for chemistry.]] In the Arab World, the Muslim were translating the works of the ancient Greeks and Egyptians into Arabic and were experimenting with scientific ideas.The History of Ancient Chemistry The development of the modern scientific method was slow and arduous, but an early scientific method for chemistry began emerging among early Muslim chemists, beginning with the 9th century chemist Jabir ibn Hayyan (known as "Geber" in Europe), who is "considered by many to be the father of chemistry". John Warren (2005). "War and the Cultural Heritage of Iraq: a sadly mismanaged affair", Third World Quarterly, Volume 26, Issue 4 & 5, p. 815-830. Dr. A. Zahoor (1997), JABIR IBN HAIYAN (Jabir), University of IndonesiaPaul Vallely, How Islamic inventors changed the world, The Independent He introduced a systematic and experimental approach to scientific research based in the laboratory, in contrast to the ancient Greek and Egyptian alchemists whose works were largely allegorical and often unintelligble.Kraus, Paul, Jâbir ibn Hayyân, Contribution à l'histoire des idées scientifiques dans l'Islam. I. Le corpus des écrits jâbiriens. II. Jâbir et la science grecque,. Cairo (1942-1943). Repr. By Fuat Sezgin, (Natural Sciences in Islam. 67-68), Frankfurt. 2002: (cf. ) He also invented and named the alembic (al-anbiq), chemically analyzed many chemical substances, composed lapidaries, distinguished between alkalis and acids, and manufactured hundreds of drugs.Will Durant (1980). The Age of Faith (The Story of Civilization, Volume 4), p. 162-186. Simon & Schuster. ISBN 0671012002. He also refined the theory of five classical elements into the theory of seven alchemical elements after identifying mercury and sulfur as chemical elements,Strathern, Paul. (2000), Mendeleyev’s Dream – the Quest for the Elements, New York: Berkley Books and he developed the theory of corpuscularianism where all physical bodies possess an inner and outer layer of minute particles or corpuscles. Among other influential Muslim chemists, Ja'far al-Sadiq,Research Committee of Strasburg University, Imam Jafar Ibn Muhammad As-Sadiq A.S. The Great Muslim Scientist and Philosopher, translated by Kaukab Ali Mirza, 2000. Willowdale Ont. ISBN 0969949014. Alkindus,Felix Klein-Frank (2001), "Al-Kindi", in Oliver Leaman & Hossein Nasr, History of Islamic Philosophy, p. 174. London: Routledge. Abu Rayhan al-Biruni,Michael E. Marmura (1965). "An Introduction to Islamic Cosmological Doctrines. Conceptions of Nature and Methods Used for Its Study by the Ikhwan Al-Safa'an, Al-Biruni, and Ibn Sina by Seyyed Hossein Nasr", Speculum 40 (4), p. 744-746. AvicennaRobert Briffault (1938). The Making of Humanity, p. 196-197. and Ibn Khaldun refuted the theories of alchemy, particularly the theory of the transmutation of metals. Rhazes refuted Aristotle's theory of four classical elements for the first time and set up the firm foundations of modern chemistry, using the laboratory in the modern sense, designing and describing more than twenty instruments, many parts of which are still in use today, such as a crucible, decensory, cucurbit or retort for distillation, and the head of a still with a delivery tube (ambiq, Latin alembic), and various types of furnace or stove.G. Stolyarov II (2002), "Rhazes: The Thinking Western Physician", The Rational Argumentator, Issue VI. Emergence of modern chemistry Pseudo-Majriti's Sage's Step/The Rank of the Wise (Rutbat al-hakim, c. 1009), later translated into Latin in 1252 (on the orders of King Alfonso X of Castile), includes alchemical formulae and instructions for purification of precious metals, and was the first to note the principle of conservation of mass, which he did in the course of his pathbreaking experiment on mercuric oxide: I took natural quivering mercury, free from impurity, and placed it in a glass vessel shaped like an egg. This I put inside another vessel like a cooking pot, and set the whole apparatus over an extremely gentle fire. The outer pot was then in such a degree of heat that I could bear my hand upon it. I heated the apparatus day and night for forty day, after which I opened it. I found that the mercury (the original weight of which was a quarter of a pound) had been completely converted into red powder, soft to touch, the weight remaining as it was originally. Nasir al-Din al-Tusi described an early version of the conservation of mass, noting that a body of matter is able to change but is not able to disappear.Farid Alakbarov (Summer 2001). A 13th-Century Darwin? Tusi's Views on Evolution, Azerbaijan International 9 (2). For the more honest practitioners in Europe, alchemy became an intellectual pursuit after early Arabic alchemy became available through Latin translation, and over time, they got better at it. Paracelsus (1493-1541), for example, rejected the 4-elemental theory and with only a vague understanding of his chemicals and medicines, formed a hybrid of alchemy and science in what was to be called iatrochemistry. Paracelsus was not perfect in making his experiments truly scientific. For example, as an extension of his theory that new compounds could be made by combining mercury with sulfur, he once made what he thought was "oil of sulfur". This was actually dimethyl ether, which had neither mercury nor sulfur. Practical attempts to improve the refining of ores and their extraction to smelt metals was an important source of information for early chemists, among them Georg Agricola (1494–1555), who published his great work De re metallica in 1556. His approach removed the mysticism associated with the subject, creating the practical base upon which others could build. The work describes the many kinds of furnace used to smelt ore, and stimulated interest in minerals and their composition. It is no coincidence that he gives numerous references to the earlier author, Pliny the Elder and his Naturalis Historia. In 1605, Sir Francis Bacon published The Proficience and Advancement of Learning, which contains a description of what would later be known as the scientific method. In 1615 Jean Beguin publishes the Tyrocinium Chymicum, an early chemistry textbook, and in it draws the first-ever chemical equation.Crosland, M.P. (1959). "The use of diagrams as chemical 'equations' in the lectures of William Cullen and Joseph Black." Annals of Science, Vol 15, No. 2, Jun. , one of the co-founders of modern chemistry through his use of proper experimentation, which further separated chemistry from alchemy]] Robert Boyle (1627–1691) is considered to have refined the modern scientific method for alchemy and to have separated chemistry further from alchemy.Robert Boyle Robert Boyle was an atomist, but favoured the word corpuscle over atoms. He comments that the finest division of matter where the properties are retained is at the level of corpuscles. Boyle was credited with the discovery of Boyle's Law. He is also credited for his landmark publication The Sceptical Chymist, where he attempts to develop an atomic theory of matter, with no small degree of success. He laid the foundations for the Chemical Revolution with his mechanical corpuscular philosophy, which in turn relied heavily on the alchemical corpuscular theory and experimental method dating back to the alchemist Geber. Despite all these advances, the person celebrated as the "father of modern chemistry" is Antoine Lavoisier who developed his law of conservation of mass in 1789, also called Lavoisier's Law.Lavoisier, Antoine (1743-1794) -- from Eric Weisstein's World of Scientific Biography, ScienceWorld With this, chemistry acquired a strict quantitative nature, allowing reliable predictions to be made. In 1754, Joseph Black isolated carbon dioxide, which he called "fixed air". Carl Wilhelm Scheele and Joseph Priestley independently isolated oxygen, called by Priestley "dephlogisticated air" and Scheele "fire air". Joseph Proust proposed the law of definite proportions, which states that elements always combine in small, whole number ratios to form compounds. In 1800, Alessandro Volta devised the first chemical battery, thereby founding the discipline of electrochemistry. In 1803, John Dalton proposed Dalton's Law, which describes relationship between the components in a mixture of gases and the relative pressure each contributes to that of the overall mixture. Antoine Lavoisier ]] Although the archives of chemical research draw upon work from ancient Babylonia, Egypt, and especially the Arabs and Persians after Islam, modern chemistry flourished from the time of Antoine Lavoisier, who is regarded as the "father of modern chemistry", particularly for his discovery of the law of conservation of mass, and his refutation of the phlogiston theory of combustion in 1783. (Phlogiston was supposed to be an imponderable substance liberated by flammable materials in burning.) Mikhail Lomonosov independently established a tradition of chemistry in Russia in the 18th century. Lomonosov also rejected the phlogiston theory, and anticipated the kinetic theory of gases. He regarded heat as a form of motion, and stated the idea of conservation of matter. The vitalism debate and organic chemistry After the nature of combustion (see oxygen) was settled, another dispute, about vitalism and the essential distinction between organic and inorganic substances, was revolutionized by Friedrich Wöhler's accidental synthesis of urea from inorganic substances in 1828. Never before had an organic compound been synthesized from inorganic material. This opened a new research field in chemistry, and by the end of the 19th century, scientists were able to synthesize hundreds of organic compounds. The most important among them are mauve, magenta, and other synthetic dyes, as well as the widely used drug aspirin. The discovery of the artificial synthesis of urea contributed greatly to the theory of isomerism, as the empirical chemical formulas for urea and ammonium cyanate can be expressed similarly. Disputes about atomism after Lavoisier by Chantrey]] Throughout the 19th century, chemistry was divided between those who followed the atomic theory of John Dalton and those who did not, such as Wilhelm Ostwald and Ernst Mach. Although such proponents of the atomic theory as Amedeo Avogadro and Ludwig Boltzmann made great advances in explaining the behavior of gases, this dispute was not finally settled until Jean Perrin's experimental investigation of Einstein's atomic explanation of Brownian motion in the first decade of the 20th century. Well before the dispute had been settled, many had already applied the concept of atomism to chemistry. A major example was the ion theory of Svante Arrhenius which anticipated ideas about atomic substructure that did not fully develop until the 20th century. Michael Faraday was another early worker, whose major contribution to chemistry was electrochemistry, in which (among other things) a certain quantity of electricity during electrolysis or electrodeposition of metals was shown to be associated with certain quantities of chemical elements, and fixed quantities of the elements therefore with each other, in specific ratios. These findings, like those of Dalton's combining ratios, were early clues to the atomic nature of matter. The periodic table , responsible for the periodic table.]] For many decades, the list of known chemical elements had been steadily increasing. A great breakthrough in making sense of this long list (as well as in understanding the internal structure of atoms as discussed below) was Dmitri Mendeleev and Lothar Meyer's development of the periodic table, and particularly Mendeleev's use of it to predict the existence and the properties of germanium, gallium, and scandium, which Mendeleev called ekasilicon, ekaaluminium, and ekaboron respectively. Mendeleev made his prediction in 1870; gallium was discovered in 1875, and was found to have roughly the same properties that Mendeleev predicted for it. The modern definition of chemistry Classically, before the 20th century, chemistry was defined as the science of the nature of matter and its transformations. It was therefore clearly distinct from physics which was not concerned with such dramatic transformation of matter. Moreover, in contrast to physics, chemistry was not using much of mathematics. Even some were particularly reluctant to using mathematics within chemistry. For example, Auguste Comte wrote in 1830: However, in the second part of the 19th century, the situation changed and August Kekule wrote in 1867: After the discovery by Ernest Rutherford and Niels Bohr of the atomic structure in 1912, and by Marie and Pierre Curie of radioactivity, scientists had to change their viewpoint on the nature of matter. The experience acquired by chemists was no longer pertinent to the study of the whole nature of matter but only to aspects related to the electron cloud surrounding the atomic nuclei and the movement of the latter in the electric field induced by the former (see Born-Oppenheimer approximation). The range of chemistry was thus restricted to the nature of matter around us in conditions which are not too far (or exceptionally far) from standard conditions for temperature and pressure and in cases where the exposure to radiation is not too different from the natural microwave, visible or UV radiations on Earth. Chemistry was therefore re-defined as the science of matter that deals with the composition, structure, and properties of substances and with the transformations that they undergo. However the meaning of matter used here relates explicitly to substances made of atoms and molecules, disregarding the matter within the atomic nuclei and its nuclear reaction or matter within highly ionized plasmas. This does not mean that chemistry is never involved with plasma or nuclear sciences or even bosonic fields nowadays, since areas such as Quantum Chemistry and Nuclear Chemistry are currently well developed and formally recognized sub-fields of study under the Chemical sciences (Chemistry), but what is now formally recognized as subject of study under the Chemistry category as a science is always based on the use of concepts that describe or explain phenomena either from matter or to matter in the atomic or molecular scale, including the study of the behavior of many molecules as an aggregate or the study of the effects of a single proton on an single atom, but excluding phenomena that deal with different (more "exotic") types of matter (e.g. Bose-Einstein condensate, Higgs Boson, dark matter, naked singularity, etc.) and excluding principles that refer to intrinsic abstract laws of nature in which their concepts can be formulated completely without a precise formal molecular or atomic paradigmatic view (e.g. Quantum Chromodynamics, Quantum Electrodynamics, String Theory, parts of Cosmology (see Cosmochemistry), certain areas of Nuclear Physics (see Nuclear Chemistry),etc.). Nevertheless the field of chemistry is still, on our human scale, very broad and the claim that chemistry is everywhere is accurate. Quantum chemistry Some view the birth of quantum chemistry in the discovery of the Schrödinger equation and its application to the hydrogen atom in 1926. However, the 1927 article of Walter Heitler and Fritz LondonW. Heitler and F. London, Wechselwirkung neutraler Atome und Homöopolare Bindung nach der Quantenmechanik, Z. Physik, 44, 455 (1927). is often recognised as the first milestone in the history of quantum chemistry.Quantum chemistry This is the first application of quantum mechanics to the diatomic hydrogen molecule, and thus to the phenomenon of the chemical bond. In the following years much progress was accomplished by Edward Teller, Robert S. Mulliken, Max Born, J. Robert Oppenheimer, Linus Pauling, Erich Hückel, Douglas Hartree, Vladimir Aleksandrovich Fock, to cite a few. Still, skepticism remained as to the general power of quantum mechanics applied to complex chemical systems. The situation around 1930 is described by Paul Dirac:P.A.M. Dirac, Quantum Mechanics of Many-Electron Systems, Proc. R. Soc. London, A 123, 714 (1929). Hence the quantum mechanical methods developed in the 1930s and 1940s are often referred to as theoretical molecular or atomic physics to underline the fact that they were more the application of quantum mechanics to chemistry and spectroscopy than answers to chemically relevant questions. In the 1940s many physicists turned from molecular or atomic physics to nuclear physics (like J. Robert Oppenheimer or Edward Teller). In 1951, a milestone article in quantum chemistry is the seminal paper of Clemens C. J. Roothaan on Roothaan equations.C.C.J. Roothaan, A Study of Two-Center Integrals Useful in Calculations on Molecular Structure, J. Chem. Phys., 19, 1445 (1951). It opened the avenue to the solution of the self-consistent field equations for small molecules like hydrogen or nitrogen. Those computations were performed with the help of tables of integrals which were computed on the most advanced computers of the time. Molecular biology and biochemistry By the mid 20th century, in principle, the integration of physics and chemistry was extensive, with chemical properties explained as the result of the electronic structure of the atom; Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more complicated molecules. However, though some principles deduced from quantum mechanics were able to predict qualitatively some chemical features for biologically relevant molecules, they were, till the end of the 20th century, more a collection of rules, observations, and recipes than rigorous ab initio quantitative methods. This heuristic approach triumphed in 1953 when James Watson and Francis Crick deduced the double helical structure of DNA by constructing models constrained by and informed by the knowledge of the chemistry of the constituent parts and the X-ray diffraction patterns obtained by Rosalind Franklin.Watson, J. and Crick, F., "Molecular Structure of Nucleic Acids" Nature, April 25, 1953, p 737–8 '' This discovery lead to an explosion of research into the biochemistry of life. In the same year, the Miller-Urey experiment demonstrated that basic constituents of protein, simple amino acids, could themselves be built up from simpler molecules in a simulation of primordial processes on Earth. Though many questions remain about the true nature of the origin of life, this was the first attempt by chemists to study hypothetical processes in the laboratory under controlled conditions. In 1983 Kary Mullis devised a method for the in-vitro amplification of DNA, known as the polymerase chain reaction (PCR), which revolutionized the chemical processes used in the laboratory to manipulate it. PCR could be used to synthesize specific pieces of DNA and made possible the sequencing of DNA of organisms, which culminated in the huge human genome project. An important piece in the double helix puzzle was solved by one of Pauling's student Matthew Meselson and Frank Stahl, the result of their collaboration (Meselson-Stahl experiment) has been called as "the most beautiful experiment in biology". They used a centrifugation technique that sorted molecules according to differences in weight. Because nitrogen atoms are a component of DNA, they were labelled and therefore tracked in replication in bacteria. Chemical industry The later part of the nineteenth century saw a huge increase in the exploitation of petroleum extracted from the earth for the production of a host of chemicals and largely replaced the use of whale oil, coal tar and naval stores used previously. Large scale production and refinement of petroleum provided feedstocks for liquid fuels such as gasoline and diesel, solvents, lubricants, asphalt, waxes, and for the production of many of the common materials of the modern world, such as synthetic fibers, plastics, paints, detergents, pharmaceuticals, adhesives and ammonia as fertilizer and for other uses. Many of these required new catalysts and the utilization of chemical engineering for their cost-effective production. In the mid-twentieth century, control of the electronic structure of semiconductor materials was made precise by the creation of large ingots of extremely pure single crystals of silicon and germanium. Accurate control of their chemical composition by doping with other elements made the production of the solid state transistor in 1951 and made possible the production of tiny integrated circuits for use in electronic devices, especially computers. See also Histories and timelines *Atomic theory *Cupellation *History of chromatography *History of electrochemistry *History of the molecule *History of molecular biology *History of the periodic table *History of physics *History of science and technology *History of thermodynamics *History of energy *Timeline of chemical elements discoveries *Timeline of chemistry *Timeline of materials technology *Timeline of atomic and subatomic physics *Timeline of thermodynamics, statistical mechanics, and random processes *List of years in science *Nobel Prize in chemistry Chemists ''listed chronologically: *List of chemists *Jabir ibn Hayyan (Geber), 722-804 *Al-Kindi (Alkindus), 801-873 *Muhammad ibn Zakariya al-Razi (Rhazes), 865-925 *Abu Rayhan al-Biruni, 973-1048 *Ibn Sina (Avicenna), 980-1037 *Nasir al-Din al-Tusi, 1201-1274 *Ibn Khaldun, 1332-1406 *Joseph Black, 1728-1799 *Joseph Priestley, 1733-1804 *Carl Wilhelm Scheele, 1742-1786 *Alessandro Volta, 1745-1827 *Jacques Charles, 1746-1823 *Claude Louis Berthollet, 1748-1822 *Joseph-Louis Gay-Lussac, 1778-1850 *Humphry Davy, 1778-1829 *Jöns Jakob Berzelius, inventor of modern chemical notation, 1779-1848 *Justus von Liebig, 1803-1873 *Louis Pasteur, 1822-1895 *Stanislao Cannizzaro, 1826-1910 *Friedrich August Kekulé von Stradonitz, 1829-1896 *Willard Gibbs, 1839-1903 *J. H. van 't Hoff, 1852-1911 *Marie Curie, 1867-1934 *Victor Grignard, 1871-1935 *Gilbert N. Lewis, 1875-1946 *Otto Hahn, 1879-1968 *Irving Langmuir, 1881-1957 *Walther Nernst, 1864-1941 *Linus Pauling, 1901-1994 *Glenn T. Seaborg, 1912-1999 *Frederick Sanger, 1918- *Rudolph A. Marcus, 1923- *Harold Kroto, 1939- *Richard Smalley, 1943-2005 *Peter Atkins, 1940- Notes References *Selected classic papers from the history of chemistry *Biographies of chemists *Eric R. Scerri, The Periodic Table: Its Story and Its Significance, Oxford University Press, 2006. Further reading * Servos, John W., [http://books.google.com/books?id=1UZjU2WfLAoC&printsec=frontcover Physical chemistry from Ostwald to Pauling : the making of a science in America], Princeton, N.J. : Princeton University Press, 1990. ISBN 0691085668 External links * ChemisLab - Chemists of the Past * SHAC: Society for the History of Alchemy and Chemistry Category:History of chemistry